Gas turbine driven generator arrangement



NOV. 14, 1939. s, PUFFER 2,180,168

GAS TURBINE DRIVEN GENERATOR ARRANGEMENT Filed June '7, 1938 3/ I so /0Inventor:

His Attorne g.

Patented Nov. 14, 1939 GAS TURBINE DRIVEN GENERATOR 'ABRAN EBIENT Sam-clR. Puller, Saagus, Masa, assignor to General Electric Company, acorporation of New York Application June 7, 1938, Serial No. 212,297

'IClaims.

The present invention relates to gas turbine driven generatorarrangements of the type in which a gas turbine is supplied with hightem-' perature combustion gases from an internal combustion engine orother source and has a bucket wheel secured to the generator shaft.Arrangements of this kind when used as auxiliary power plants foraircraft necessitate a compact design due to the relatively small spaceavailable and the provision of special cooling means for the generator.

The object of my invention is to provide an improved construction andarrangement of gas turbine driven generators which occupy little space,permit eifective cooling of the generator and may be operated withsafety and high efficiency.

For a consideration of what I believe to be novel and my invention,attention is directed to the following description and the claimsappended thereto in connection with the accompanying drawing.

The single figure of the drawing illustrates a sectional view of a gasturbine driven generator arrangement in accordance with my invention.

The arrangement comprises an electric generator III with an outer casingI I and a shaft I2. The rotor of the generator includes a magnetic pathformed by laminated iron l3 fastened to the shaft and a winding I4secured to the lamination and slip rings l5 insulated from the shaft forconducting exciting current to the winding I4. The stator of thegenerator has a magnetic path formed by slotted laminated iron I6supported on the casing and forming a support of ducts II between theouter surface of the lamination and the casing II. windings I6 areembedded in the slots of the stator laminations near'an airgap I3between the rotor and the stator. The rotor with the shaft I2 issupported by bearings 20 and 2| respectively, the bearing 26 being heldon a detachable end shield 22 of the generator. This end shield hasflanges 23 secured to corresponding flanges of the casing II. Thebearing M is supported on the right hand end shield 24 of the generator,which shield in the present instance is formed by an exten-- sion of thecasing II. The generator is driven by a gas turbine 25 which includes asingle bucket wheel 26 secured to a right-hand, overhung portion 21 ofthe shaft I2. Gas, such as exhaust gas from an internal combustionengine, is conducted to the bucket wheel 26 by means of a nozzle box 26disposed intermediate the bucket wheel 26 and the generator casing IIand having a flanged inlet conduit 29. The nozzle box 26 forms aplurality of nozzles 30 for properly discharging gas into passagesformed by buckets 3| of the bucket wheel. The compact arrangement, thatis, the .close spacing of the 5 gas turbine and the generator, requiresthe provision of special-cooling means for the generator to protect thelatter against high temperature due to radiation and convection from thehigh temperature gas turbine. To this end the gen- 10 erator is providedwith a built-in centrifugal type compressor for forcing air through thegaps and ducts formed by the generator, towards the bucket wheel andalong a special channel formed between the generator casing and the gasturbine nozzle box. More specifically, in the present arrangement thedetachable end shield 22 of the generator forms an annular inlet channel32 with a flanged inlet opening 33 of a centrifugal compressor. Thelatter also includes an impeller 34 with a row of blades 35 forcompressing air received from the inlet channel 32. The air dischargedfrom the impeller 34 is conducted through a diffuser 36 whereby velocityenergy of the air discharged from the impeller 34 is converted intopressure energy. The diffuser 36 has a side wall 31 which forms an endwall of the compressor. The compressed air discharged by the diffuser 36is forced through the ducts I'I formed in the circumferential part ofthe generator stator and also through the gap formed between the statorand rotor, as well as through other ducts and spaces formed by thewindings and other parts of the generator effectively to cool thelatter. In order to reduce the amount of air forced through the largeducts I1 and assure the flow of suflicient cooling air through the othergaps and spaces in the generator, a flared ring 38 is provided ahead ofthe inlets of the ducts I! as regards the direction of flow. The airleaving the generator proper is conducted through channels 39 formedbetween the right-hand end portion of the casing II and the casing ofthe bearing M. The channels 39 are extended by a shield 40 secured atits left-hand end to the extension 24 of the easing I l and opening atits right-hand end towards the bucket wheel. With the provision of theshield 46 the casing of the bearing 2| is continuously cooled duringoperation by a stream of cooling air. The air discharged from theopening of the end shield 40 is forced towards the central portion ofthe bucket wheel 26, whence it flows through an annular channel 4|formed between the extensions 24, 40 of the generator casing II and aprotecting shield 42 arranged intermediate the turbine casing and thegas turbine nozzle box. This end shield 42 confines the cooling airdischarged from the generator in the comparatively narrow channel 4| andthereby assures effective cooling of the outer surface of the generatorcasing and at the same time it reduces heating of the generator casingdue to radiation and convection of heatfrom the gas turbine nozzle box.

A machine 43 which may be an oil pump or an exciter; for the generatoris connected to an overhung portion of the left-hand end of thegenerator shaft l2. For the purposes of compactness of the constructionand stability of operation, the machine 43 has a shaft 44 arranged atright angles with the generator shaft I2 and driven therefrom by a wormgear including a worm 45 fastened to the left-hand, overhung portion ofthe shaft l2 and a gear 46 secured to the shaft 44 and meshing with theworm 45. The gearing 45, 46 is enclosed in a. casing which includes anextension 41 of the end shield 22 and ar'iiend plate 48 flanged to theextension 41.

Having described themethod of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Gas turbine driven generator arrangement including the combination ofan electric generator having a rotor shaft, a casing, bearingssupporting the shaft on the casing, a gas turbine including a bucketwheel secured to the shaft, and means for cooling the generator andbucket wheel comprising a centrifugal type compressor built into thegenerator to force air through the latter and discharge it towards thebucket wheel.

2. Gas turbine driven generator arrangement including an electricgenerator having a shaft and a casing, a bearing for the shaft supportedinside an end portion of the casing, a gas turbine having a bucket wheelsecured to the shaft adiacerit the bearing and a nozzle box surroundingthe shaft intermediate the bucket wheel and the casing, the generatorhaving a detachable end shield opposite the bucket wheel, and means forcooling the generator comprising a centrifugal type compressor builtinto the generator and having an inlet channel defined by the endshield.

3. Gas turbine driven generator arrangement including an electricgenerator having a shaft, a

casing forming a plurality of ducts and gaps for cooling air, a bearingfor the shaft surrounded by and supported on an end portion of thecasing, a gas turbine including a bucket wheel secured to the shaftadjacent the bearing and a nozzle box between the bucket wheel and thecasing; a shield between the casing and the nozzle box to protect thecasing against heat from the nomle box and to form a channel with thecasing, and means including a centrifugal type supercharger with adiffuser built into the generator to force cooling air through saidducts, gaps and channels.

4. Gas turbine driven generator arrangement including a generator havinga casing and a shaft supported on the casing and forming overhungportions, a gas turbine for driving the generator having a bucket wheelsecured to one of the overhung portions, and an exciter for thegenerator having a shaft driven from the other overhung portion of thegenerator shaft and being mounted at a right angle thereto.

5. Gas turbine driven generator arrangement including a generator havinga casing and a shaft supported on the casing and forming overhungportions, a gas turbine for driving the generator having a bucket wheelsecured to one of the overhung portions, a machine associated with thegenerator having a shaft driven from the other overhung portion of thegenerator shaft and being mounted at a right angle thereto, and meansincluding a centrifugal type compressor with a diffuser builtinto thecasing to cool the generator and the bucket wheel.

6. Gas turbine driven generator arrangement including the combination ofan electric generator having a shaft, a gas turbine having a bucketwheel, and means for cooling the generator and the bucket wheelcomprising a pump for forcing air through the generator, the generatorhaving a casing with an opening adjacent the bucket wheel to dischargecooling air from the generator through the opening towards the bucketwheel.

7. Gas turbine driven generator arrangement including the combination ofan electric generator having a casing with an open end portion and ashaft, a gas turbine with a bucket wheel secured to an overhung portionof the shaft near the open end portion, and means disposed at leastpartly within the other end portion of the generator casing for forcingcooling air through the generator and discharge it through the openingin the first mentioned casing end portion towards the bucket wheel.

SAMUEL R. PUFFER.

